LCZ scheme for assessing Urban Heat Island intensity in a complex urban area (Beirut, Lebanon).

Thermal remote sensing has become widely used to monitor and study Urban Heat Island (UHI) by the use of satellite Land Surface Temperature (LST) data, and the Local Climate Zone (LCZ) scheme has established itself as the standard for assessing Urban Heat Island Intensity (UHII). A lot of research on LST-LCZ relationship has been done, but mainly in flat terrain. Some studies on UHI in mountainous areas have been conducted, but most of them considered the combined effect of land use/land cover and topography on temperature. To the best of our knowledge no study has been carried out on the LST-LCZ relationship in a complex topography area after removing the topography effect. This paper presents a methodology for assessing the impact of the urban structure on UHII in Beirut, a coastal city with heterogenous urban morphology and complex topography. It was concluded that the main urban variables which contribute to the spatial variability of topographically normalized LST are, in decreasing order of relative importance, the built-up ratio, the pervious surface ratio, the buildings' mean height and mean surface area. The difference in average temperatures between high-rise densely built LCZs and mostly pervious zones exceeded two degrees at nighttime. • Assess the relationship topographically normalized LST/LCZ at fine scale in a complex environment. • Correct LST for topographic effect with Random Forest regression. • Identify LCZ groups which differ regarding their mean normalized LST with ANOVA. • Normalized LST follows LCZ spatial structure. • Normalized LST is related to built-up ratio, pervious surface ratio, buildings' mean height and mean surface area. [ABSTRACT FROM AUTHOR]